The field of the present invention is the manufacture and use of lids for containers. More particularly, the present invention relates to lids for use on specimen plates, such as microplates.
Specimen plates are used in several industries, such as the biotechnology and biomedical industries. The specimen plates can be used, for example, to hold multiple compounds or materials, to conduct multiple assays on one or more compounds, to facilitate high throughput screening and to accelerate the production and testing of a large number of samples. For the purpose of this discussion, the term xe2x80x9cspecimenxe2x80x9d or xe2x80x9csamplexe2x80x9d refers to chemicals, assays, reagents, genetic material, biological compounds, or therapeutic material, in any form, such as a liquid, gel, or solid form.
Typically a specimen plate has multiple sample wells on its top surface into which one or more specimen can be placed, although a particular sample plate may have only a single well for the entire plate. Each of the wells forms a container into which a specimen is placed. The specimen plate also can be heated, cooled, or shaken to facilitate a desired process. Specimen plates are configured to meet industry standards. For example, some commonly used standard plates have 96, 384, or 1536 wells. Other sample plates are configured with 1, 2, 4, 6, 12, 24 or 48 wells. Such plates are available from, for example, Greiner America Corp., P.O. Box 953279, Lake Mary, Fla. 32795-3279. Plates may be handled manually or robotically.
It is known to use specimen plates in conjunction with automated processing equipment, such as high throughput screening equipment. Automated equipment, such as automated liquid dispensers, can receive appropriately configured specimen plates and deposit samples or reagents into the plate wells. Other known automated equipment facilitates the processing and testing of specimens using loaded specimen plates.
It is also known to provide a lid to cover a specimen plate. This is desirable in some applications. For example, the samples in the wells may need to incubate, or it may be desired to store the samples for an extended period of time. By covering the wells, contamination and evaporation may be reduced. Wells located near the edges of some known sample plates also can be prone to increased evaporation relative to middle wells when covered by a lid. This phenomena is often referred to as an xe2x80x9cEdge Effect.xe2x80x9d Such sample plates suffer a deficiency of non-uniform drying, which may cause inaccuracy in testing or assay procedures or other inefficiencies in automated processes.
It is known to cover a sample plate manually, such as by positioning a plastic lid over the top of the specimen plate. One such plastic lid is Model No. 656191 from Greiner America Corp., P.O. Box 953279, Lake Mary, Fla. 32795-3279. Such plastic lids suffer a deficiency in that it is difficult to form an air tight seal between the lid and specimen plate, leading to evaporation and the possibility of contamination. One known way to reduce those effects is to adhere tape around the edges of the plastic lid to seal the plastic lid to the plate. This makes access to the wells difficult in that the tape needs to be removed to gain access. In addition, adhesive residue can remain on the edges of the plate and lid, leading to the possibility of further contamination or difficulty in handling. Moreover, this covering and uncovering process is relatively time consuming and requires some manual dexterity. Substantial handling of the specimen plate is also required, which may undesirably agitate the contents of the wells and lead to inaccurate results. Alternatively, a foil tape can be applied directly to the top of the wells. Such foil tape also suffers from being time consuming to apply, increased contamination risk, and undue agitation.
Accordingly, there is a need for a specimen plate lid that provides enhanced sealing and provides increased efficiency in placement on a specimen plate or removal from a specimen plate. Further, there is a need for a specimen plate with improved gas exchange characteristics.
The present invention alleviates to a great extent the disadvantages of the known specimen plate lids and methods of using them by providing a specimen plate lid having a seal between a lower surface of the lid and a mating upper surface of a specimen plate. Generally, the lid includes a plate member having an exterior surface that is exposed when placed on a specimen plate, and an lower/inner surface that faces the specimen plate when placed on top of the specimen plate. Preferably a side portion extends from the periphery of the lower/inner surface so that the side portion overlaps with side surfaces of the specimen plate when the lid is placed over the specimen plate. The side portion has an exterior surface that is exposed and an inner surface facing the specimen plate when the lid is placed over the specimen plate.
Alignment tabs preferably are located on the side portion and cooperative mating elements are located on the specimen plate to assist in guiding the lid onto the specimen plate and in providing a desired registration with the specimen plate. The lower surface of the lid has a sealing perimeter constructed to cooperate with a complementary sealing surface on the specimen plate. A seal formed from a compliant sealing material is positioned between the lower surface of the lid and the specimen plate. The seal is shaped to cooperate with both the sealing perimeter on the lid and the complementary sealing surface on the specimen plate. Preferably seal retaining members are provided on the sealing perimeter of the lid to retain the seal in place. The lid also preferably has sufficient weight to compress the seal when the lid is aligned and positioned on the specimen plate. In this way, the weight of the lid provides a gravitational force sufficient to compress the seal against the sealing surface on the specimen plate, enhancing the level of diffusion resistance.
It is an advantage of the present invention that the specimen plate lid can be accurately and relatively efficiently positioned on a specimen plate. Since the lid and its compressible seal alone provide a good barrier between the specimen plate wells and the outside environment, additional mechanical or adhesive sealing is not required. This saves material and also can reduce the time required to cover and seal a specimen plate. Moreover, agitation and other disturbance of the specimen material in the wells can be minimized.
It is a further advantage that the specimen plate lid is well suited for handling by a robotic material handling system. For example, the lid is generally self-aligning, permitting the lid to be easily positioned by robotic handling. Additionally, since the lid is self-sealing with the specimen plate, operator intervention is not required to mechanically seal the plate.
These and other features and advantages of the present invention will be appreciated from review of the following detailed description of the invention, along with the accompanying figures in which like reference numerals refer to like parts throughout.